Links for Keyword: Brain imaging

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By Sidney Perkowitz In 2019, Edward Chang, a neurosurgeon at the University of California, San Francisco, opened the skull of a 36-year-old man, nicknamed “Pancho,” and placed a thin sheet of electrodes on the surface of his brain.1 The electrodes gather electrical signals from the motor neurons that control the movement of the mouth, larynx, and other body parts to produce speech. A small port, implanted on top of Pancho’s head, relayed the brain signals to a computer. This “brain-computer interface,” or BCI, solved an intractable medical problem. In 2003, Pancho, a field worker in California’s vineyards, was involved in a car crash. Days after undergoing surgery, he suffered a brainstem stroke, reported the New York Times Magazine.2 The stroke robbed Poncho of the power of speech. He could communicate only by laboriously spelling out words one letter at a time with a pointing device. After training with the computer outfitted with deep-learning algorithms that interpreted his brain activity, Pancho could think the words that he wanted to say, and they would appear on the computer screen. Scientists called the results “groundbreaking”; Pancho called them “life-changing.” The clinical success of BCIs (there are other stories to go along with Pancho’s) appear to vindicate the futurists who claim that BCIs may soon enhance the brains of healthy people. Most famously, Ray Kurzweil, author of The Singularity Is Near, has asserted that exponentially rapid developments in neuroscience, bioscience, nanotechnology, and computation will coalesce and allow us to transcend the limitations of our bodies and brains. A major part of this huge shift will be the rise of artificial intelligences that are far more capable than human brains. It is an inevitability of human evolution, Kurzweil thinks, that the two kinds of intelligence will merge to form powerful hybrid brains, which will define the future of humanity. This, he predicted, would happen by 2045. While futuristic scenarios like Kurzweil’s are exciting to ponder, they are brought back down to Earth by the technological capabilities of brain-computer hybrids as they exist today. BCIs are impressive, but the path from helping stroke victims to giving people superpowers is neither direct nor inevitable. © 2022 NautilusThink Inc,

Related chapters from BN: Chapter 11: Motor Control and Plasticity; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28570 - Posted: 11.30.2022

By Laura Sanders SAN DIEGO — Scientists have devised ways to “read” words directly from brains. Brain implants can translate internal speech into external signals, permitting communication from people with paralysis or other diseases that steal their ability to talk or type. New results from two studies, presented November 13 at the annual meeting of the Society for Neuroscience, “provide additional evidence of the extraordinary potential” that brain implants have for restoring lost communication, says neuroscientist and neurocritical care physician Leigh Hochberg. Some people who need help communicating can currently use devices that require small movements, such as eye gaze changes. Those tasks aren’t possible for everyone. So the new studies targeted internal speech, which requires a person to do nothing more than think. “Our device predicts internal speech directly, allowing the patient to just focus on saying a word inside their head and transform it into text,” says Sarah Wandelt, a neuroscientist at Caltech. Internal speech “could be much simpler and more intuitive than requiring the patient to spell out words or mouth them.” Neural signals associated with words are detected by electrodes implanted in the brain. The signals can then be translated into text, which can be made audible by computer programs that generate speech. That approach is “really exciting, and reinforces the power of bringing together fundamental neuroscience, neuroengineering and machine learning approaches for the restoration of communication and mobility,” says Hochberg, of Massachusetts General Hospital and Harvard Medical School in Boston, and Brown University in Providence, R.I. © Society for Science & the Public 2000–2022.

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28556 - Posted: 11.16.2022

By Elena Renken The brain’s lifeline, its network of blood vessels, is like a tree, says Mathieu Pernot, deputy director of the Physics for Medicine Paris Lab. The trunk begins in the neck with the carotid arteries, a pair of broad channels that then split into branches that climb into the various lobes of the brain. These channels fork endlessly into a web of tiny vessels that form a kind of canopy. The narrowest of these vessels are only wide enough for a single red blood cell to pass through, and in one important sense these vessels are akin to the tree’s leaves. “When you want to look at pathology, usually you don’t see the sickness in the tree, but in the leaves,” Pernot says. (You can identify Dutch Elm Disease when the tree’s leaves yellow and wilt.) Just like leaves, the tiniest blood vessels in the brain often register changes in neuron and synapse activity first, including illness, such as new growth in a cancerous brain tumor.1, 2 But only in the past decade or so have we developed the technology to detect these microscopic changes in blood flow: It’s called ultrafast ultrasound. Standard ultrasound is already popular in clinical imaging given that it is minimally invasive, low-cost, portable, and can generate images in real time.3 But until now, it has rarely been used to image the brain. That’s partly because the skull gets in the way—bone tends to scatter ultrasound waves—and the technology is too slow to detect blood flow in the smaller arteries that support most brain function. Neurologists have mostly used it in niche applications: to examine newborns, whose skulls have gaps between the bone plates, or to guide surgeons in some brain surgeries, where part of the skull is typically removed. Neuroscience researchers have also used it to study functional differences between the two hemispheres of the brain, based on imaging of the major cerebral arteries, by positioning the device over the temporal bone window, the thinnest area of the skull. © 2022 NautilusThink Inc,

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 28536 - Posted: 11.02.2022

McKenzie Prillaman A twist on functional magnetic resonance imaging (fMRI) offers a multi-fold improvement in its time sensitivity, better enabling it to unveil the fine-scale dynamics underlying mental processes. Researchers published the results on 13 October in Science1. Can brain scans reveal behaviour? Bombshell study says not yet A standard fMRI technique measures brain activity indirectly, by tracking increases in blood flow in regions where neurons are suddenly consuming more oxygen. This signal, however, can lag behind neuronal activity by 1 second, which dampens time sensitivity — the speedy cells take mere milliseconds to send messages to one another. Jang-Yeon Park, an MRI physicist at Sungkyunkwan University in Suwon, South Korea, set out to enhance fMRI’s temporal precision to track neuronal activity on the order of milliseconds. He and his colleagues accomplished this by changing the software of a high-intensity MRI scanner to acquire data every 5 milliseconds — about 8 times faster than what the standard technique can capture — and applying frequent, repetitive stimulation to animals they were testing. This suppressed the slower-paced blood oxygenation signal, making it possible to observe faster-paced brain activity. The researchers named their technique direct imaging of neuronal activity, or DIANA. In the study, an anaesthetized mouse inside an MRI scanner received a minor electric shock to its face every 200 milliseconds. Between shocks, the machine acquired data from one tiny region of the mouse’s brain every 5 milliseconds. It moved on to a new area after the next electric shock. After the software stitched everything together, the process produced a head-on image of one full slice of the brain, capturing neuronal activity over a 200-millisecond time period. (Spatial resolution was 0.22 millimetres, which is standard for high-intensity MRI.) During the scan, the facial stimulation activated a part of the brain that processes sensory inputs, causing the region to light up with a signal. The researchers found that this ‘DIANA response’ happened at the same time that neurons fired off signals, or ‘spiked’ — activity that was measured separately, using a surgically inserted probe. Furthermore, the team was able to trace the DIANA signal through a brain circuit as groups of neurons sequentially triggered each other. © 2022 Springer Nature Limited

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28515 - Posted: 10.15.2022

By Claudia Lopez Lloreda If you look at parts of the circulatory system of whales and dolphins, you might think that you are looking at a Jackson Pollock painting, not blood vessels. These cetaceans have especially dense, complex networks of blood vessels mainly associated with the brain and spine, but scientists didn’t know why. A new analysis suggests that the networks protect cetaceans’ brains from the pulses of blood pressure that the animals endure while diving deep in the ocean, researchers report in the Sept. 23 Science. Whales and dolphins “have gone through these really amazing vascular adaptations to support their brain,” says Ashley Blawas, a marine scientist at the Duke University Marine Lab in Beaufort, N.C., who was not involved with the research. Called retia mirabilia, which means “wonderful nets,” the blood vessel networks are present in some other animals besides cetaceans, including giraffes and horses. But the networks aren’t found in other aquatic vertebrates that move differently from whales, such as seals. So scientists had suspected that the cetaceans’ retia mirabilia play a role in controlling blood pressure surges. When whales and dolphins dive, they move their tail up and down in an undulating manner, which creates surges in blood pressure. Land animals that experience similar surges, like galloping horses, are able to release some of this pressure by exhaling. But some cetaceans hold their breath to dive for long periods of time (SN: 9/23/20). Without a way to relieve that pressure, those blasts could tear blood vessels and harm other organs, including the brain. In the new study, biomechanics researcher Margo Lillie of the University of British Columbia in Vancouver and colleagues used data on the morphology of 11 cetacean species to create a computational model that can simulate the animals’ retia mirabilia. It revealed that the arteries and veins in this tangle of blood vessels are really close and may even sometimes be joined. As a result, the retia mirabilia could equalize the differences in blood pressure generated by diving, perhaps by redistributing the blood pulses from arteries to veins and vice versa. This way, the networks get rid of, or at least weaken, huge blood pressure surges that might otherwise reach and devastate the brain. © Society for Science & the Public 2000–2022.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 28499 - Posted: 10.05.2022

Scientists know both a lot and very little about the brain. With billions of neurons and trillions of connections among them, and the experimental limitations of examining the seat of consciousness and bodily function, studying the human brain is a technical, theoretical and ethical challenge. And one of the biggest challenges is perhaps one of the most fundamental – seeing what it looks like in action. The U.S. Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative is a collaboration among the National Institutes of Health, Defense Advanced Research Projects Agency, National Science Foundation, Food and Drug Administration and Intelligence Advanced Research Projects Activity and others. Since its inception in 2013, its goal has been to develop and use new technologies to examine how each neuron and neural circuit comes together to “record, process, utilize, store, and retrieve vast quantities of information, all at the speed of thought.” Just as genomic sequencing enabled the creation of a comprehensive map of the human genome, tools that elucidate the connection between brain structure and function could help researchers answer long-standing questions about how the brain works, both in sickness and in health. These five stories from our archives cover research that has been funded by or advances the goals of the BRAIN Initiative, detailing a slice of what’s next in neuroscience. Attempts to map the structure of the brain date back to antiquity, when philosophers and scholars had only the unaided eye to map anatomy to function. New visualization techniques in the 20th century led to the discovery that, just like all the other organs of the body, the brain is composed of individual cells – neurons. © 2010–2022, The Conversation US, Inc.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 13: Memory and Learning
Link ID: 28421 - Posted: 08.06.2022

By Hilary Achauer I sat in a dark room, eyes closed, with a device strapped to my head that looked like a futuristic bike helmet. For 10 minutes, while I concentrated on not accidentally opening my eyes, the prongs sticking out of this gadget and onto my scalp measured a health marker I never thought to assess: my cognitive health. When I booked my brain wave recording (also known as electroencephalography, or EEG), I expected to pull up to an office park with medical clinic vibes, but instead my GPS led me to an ocean-view storefront decorated like a cross between a surf shop and a luxury spa, with a sign in the window promising “Mental Wellness, Reimagined.” Located in Cardiff-by-the-Sea, a wealthy coastal town north of San Diego, Wave Neuroscience promises to help your brain perform better with a noninvasive treatment that uses magnets on the brain. We’re talking mental clarity, improved focus and concentration, and even a shift in mood. As a 48-year-old whose work requires focus and creativity, I was intrigued, but also nervous. Should I mess with a brain that, while not perfect, functions reasonably well? Advertisement Getting the EEG, which costs $100, was like meditating with a device strapped to my head, but it was more relaxing than that sounds. The tech gave me periodic updates, letting me know how much time had elapsed, and afterward I was ushered into an office where I met with Alexander Ring, director of applied science at Wave Neuroscience, via Zoom. Together we reviewed my “braincare report,” a one-page analysis generated in five minutes, comparing my brain waves with Wave Neuroscience’s database of tens of thousands of EEGs. Ring said my brain was generally performing well and that I showed cognitive flexibility and a capability to focus under pressure, but that I had a little bit more theta activity, or slow brain waves, than they normally like to see. He also pointed out a slight frequency mismatch between the back and front of my brain, which might affect my concentration and cause me to have to reread a paragraph to absorb the information. Rude, but accurate. © 2022 The Slate Group LLC. All rights reserved.

Related chapters from BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 14: Attention and Higher Cognition
Link ID: 28347 - Posted: 06.01.2022

By Monique Brouillette Neuroscientists have long aspired to understand the intangible properties of the mind. Our most treasured cerebral qualities, like the ability to think, write poetry, fall in love and even envision a higher spiritual realm, are all generated in the brain. But how the squishy, pinkish-gray, wrinkled mass of the physical brain gives rise to these impalpable experiences remains a mystery. Some neuroscientists think the key to cracking that mystery is a better map of the brain’s circuitry. Nearly 40 years ago, scientists achieved a milestone by completing a wiring diagram that traced all the connections of the 302 neurons of the roundworm Caenorhabditis elegans. They were traced by hand on printed sheets of electron microscope images, a meticulous and herculean task that took years to complete. The project marked the first-ever complete connectome — a comprehensive map of the neuronal connections in an animal’s nervous system. Today, thanks to advances in computing and image analysis algorithms, it can take less than a month to map a roundworm’s connectome. These technological improvements mean that scientists can set their sights on larger animals. They are closing in on the connectome of fruit fly larvae, with more than 9,000 cells, and adult flies, with 100,000 neurons. Next, they hope to map the brain of a developing fish and, perhaps within the next decade, a mouse, with roughly 70 million neurons — a project nearly a thousand times more ambitious than any done so far. And they have already started to map small pieces of the human brain, an unfathomable quest when the worm connectome was initially mapped. © 2022 Annual Reviews

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28308 - Posted: 04.30.2022

By Kim Tingley In March, neuroscientists and psychiatrists from the School of Medicine at Washington University, St. Louis, along with colleagues elsewhere, published a study in the journal Nature that sparked widespread discussion in their fields. Researchers, the study noted, are increasingly using magnetic resonance imaging — which can reveal the brain’s structure and activity — to try to find links between what is seen on an M.R.I., like cortical thickness or patterns of connection, and complicated psychological traits, like cognitive ability or mental-health conditions. In theory, such so-called brain-wide association studies could yield incredibly valuable insights. Knowing that a particular neurological feature makes someone more vulnerable to autism, Alzheimer’s or another disorder, for example, could help predict, prevent or treat that condition. Likewise, if we can link certain features to desirable traits, like academic achievement, it might be possible to take advantage of that knowledge. The problem, the Nature authors argued, is that neuroscientists often are searching for those associations in groups of study subjects that are too small, leading to results that are statistically “underpowered.” In general, they calculated, thousands of subjects should be included for a brain-wide association study to produce a finding that other studies can replicate. This was unwelcome news to many, in large part because M.R.I. machines are incredibly expensive to use, often at about $1,000 per hour, and funding is limited. Specific instances of underpowered studies are legion. So much so, says Terry Jernigan, director of the Center for Human Development at the University of California, San Diego, that singling out an example “would simply be unfair.” Indeed, according to a paper from 2020 in NeuroImage, the average number of study subjects in more than a thousand of the most cited brain-imaging papers, published between 1990 and 2012, was 12; the Nature paper calculated that the median sample size for neuroimaging studies uploaded to a popular open-access platform as of September 2021 was 23. © 2022 The New York Times Company

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28294 - Posted: 04.20.2022

Liam Drew James Johnson hopes to drive a car again one day. If he does, he will do it using only his thoughts. In March 2017, Johnson broke his neck in a go-carting accident, leaving him almost completely paralysed below the shoulders. He understood his new reality better than most. For decades, he had been a carer for people with paralysis. “There was a deep depression,” he says. “I thought that when this happened to me there was nothing — nothing that I could do or give.” But then Johnson’s rehabilitation team introduced him to researchers from the nearby California Institute of Technology (Caltech) in Pasadena, who invited him to join a clinical trial of a brain–computer interface (BCI). This would first entail neurosurgery to implant two grids of electrodes into his cortex. These electrodes would record neurons in his brain as they fire, and the researchers would use algorithms to decode his thoughts and intentions. The system would then use Johnson’s brain activity to operate computer applications or to move a prosthetic device. All told, it would take years and require hundreds of intensive training sessions. “I really didn’t hesitate,” says Johnson. The first time he used his BCI, implanted in November 2018, Johnson moved a cursor around a computer screen. “It felt like The Matrix,” he says. “We hooked up to the computer, and lo and behold I was able to move the cursor just by thinking.” Johnson has since used the BCI to control a robotic arm, use Photoshop software, play ‘shoot-’em-up’ video games, and now to drive a simulated car through a virtual environment, changing speed, steering and reacting to hazards. “I am always stunned at what we are able to do,” he says, “and it’s frigging awesome.” © 2022 Springer Nature Limited

Related chapters from BN: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 28292 - Posted: 04.20.2022

by Niko McCarty A new miniature, head-mounted microscope can simultaneously record the activity of thousands of neurons at different depths within the brains of freely moving mice. The smallest functional two-photon microscope to date, it can image neurons almost anywhere in the brain, with subcellular resolution. The device, called MINI2P (miniature two-photon microscope), can also collect data from the same cluster of neurons over several weeks, making it useful for long-term behavioral studies. “If you really want to understand what is behind cognition or failures in cognition, like in autism, you need to look at the interaction between neurons,” says lead investigator Edvard Moser, professor of neuroscience at the Kavli Institute for Systems Neuroscience in Trondheim, Norway. Other devices that measure neuronal activity, such as Neuropixels 2.0, record signals from more than 10,000 sites in the brain at once. But they have a low spatial resolution and cannot always determine which specific neuron is firing at any given time. Other miniature microscopes have also, traditionally, relied on visible light, which illuminates the surface of tissue, but are limited to imaging about 2,000 neurons. The new device can monitor a brain area measuring 500 by 500 micrometers and can capture data on more than 10,000 neurons at once. A typical mouse brain is roughly the size of a pea and contains about 85 million neurons. The MINI2P uses infrared light to capture the activity of neurons engineered to express GCaMP, a protein that binds to calcium ions during an action potential and emits a fluorescent signal in reply. The microscope measures that fluorescence using an infrared laser beam. © 2022 Simons Foundation

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28282 - Posted: 04.13.2022

By Benjamin Ehrlich Hour after hour, year after year, Santiago Ramón y Cajal sat alone in his home laboratory, head bowed and back hunched, his black eyes staring down the barrel of a microscope, the sole object tethering him to the outside world. His wide forehead and aquiline nose gave him the look of a distinguished, almost regal, gentleman, although the crown of his head was as bald as a monk’s. He had only a crowd of glass bottles for an audience, some short and stout, some tall and thin, stopped with cork and filled with white powders and colored liquids; the other chairs, piled high with journals and textbooks, left no room for anyone else to sit. Stained with dye, ink and blood, the tablecloth was strewn with drawings of forms at once otherworldly and natural. Colorful transparent slides, mounted with slivers of nervous tissue from sacrificed animals still gummy to the touch from chemical treatments, lay scattered on the worktable. With his left thumb and forefinger, Cajal adjusted the corners of the slide as if it were a miniature picture frame under the lens of his microscope. With his right hand, he turned the brass knob on the side of the instrument, muttering to himself as he drew the image into focus: brownish-black bodies resembling inkblots and radiating threadlike appendages set against a transparent yellow background. The wondrous landscape of the brain was finally revealed to him, more real than he could have ever imagined. In the late 19th century most scientists believed the brain was composed of a continuous tangle of fibers as serpentine as a labyrinth. Cajal produced the first clear evidence that the brain is composed of individual cells, later termed neurons, that are fundamentally the same as those that make up the rest of the living world. He believed that neurons served as storage units for mental impressions such as thoughts and sensations, which combined to form our experience of being alive: “To know the brain is equivalent to ascertaining the material course of thought and will,” he wrote. The highest ideal for a biologist, he declared, is to clarify the enigma of the self. In the structure of neurons, Cajal thought he had found the home of consciousness itself. © 2022 Scientific American

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28278 - Posted: 04.13.2022

By Matt Richtel For two decades, researchers have used brain-imaging technology to try to identify how the structure and function of a person’s brain connects to a range of mental-health ailments, from anxiety and depression to suicidal tendencies. But a new paper, published Wednesday in Nature, calls into question whether much of this research is actually yielding valid findings. Many such studies, the paper’s authors found, tend to include fewer than two dozen participants, far shy of the number needed to generate reliable results. “You need thousands of individuals,” said Scott Marek, a psychiatric researcher at the Washington University School of Medicine in St. Louis and an author of the paper. He described the finding as a “gut punch” for the typical studies that use imaging to try to better understand mental health. Studies that use magnetic-resonance imaging technology commonly temper their conclusions with a cautionary statement noting the small sample size. But enlisting participants can be time-consuming and expensive, ranging from $600 to $2,000 an hour, said Dr. Nico Dosenbach, a neurologist at Washington University School of Medicine and another author on the paper. The median number of subjects in mental-health-related studies that use brain imaging is around 23, he added. But the Nature paper demonstrates that the data drawn from just two dozen subjects is generally insufficient to be reliable and can in fact yield “massively inflated” findings,” Dr. Dosenbach said. For their analysis, the researchers examined three of the largest studies using brain-imaging technology to reach conclusions about brain structure and mental health. All three studies are ongoing: the Human Connectome Project, which has 1,200 participants; the Adolescent Brain Cognitive Development, or A.B.C.D., study, with 12,000 participants; and the U.K. Biobank study, with 35,700 participants. The authors of the Nature paper looked at subsets of data within those three studies to determine whether smaller slices were misleading or “reproducible,” meaning that the findings could be considered scientifically valid. © 2022 The New York Times Company

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28245 - Posted: 03.19.2022

by Niko McCarty The ‘opto’ in optogenetics — the powerful method some autism researchers use to control neurons in mice and other animals — comes from the Greek optós, meaning visible. It’s a nod to the blue light used to switch on select neurons. A new technique can do the same, albeit with something invisible: sound. In a study published in Nature Communications this month, researchers engineered neurons in the motor cortex of mice to express an ultrasound-sensitive ion channel protein called hsTRPA1. They placed an ultrasound transducer near the animal’s skull and switched it on. The response? A flex of a muscle, a perceptible twitch. The approach, called sonogenetics, enables noninvasive control over any neural circuit that can be manipulated with optogenetics, an invasive method, says lead investigator Sreekanth Chalasani, associate professor in the Molecular Neurobiology Laboratory at the Salk Institute for Biological Studies in La Jolla, California. Spectrum spoke to Chalasani about his early experiments in Caenorhabditis elegans, lucky number 63 and how sonogenetics could one day have clinical applications. Spectrum: Our readers might be familiar with optogenetics, but I’m assuming sonogenetics is new for most people. Sreekanth Chalasani: Yeah. Well, the idea in sonogenetics is that we want to manipulate things noninvasively. Ultrasound can travel through bone and skin, into the body. We’ve been using it for decades. It’s safe. The question is: Can we leverage it to get in the body and control cells, like with optogenetics? S: Literally controlling cells with sound. SC: Right. In optogenetics, light triggers action potentials in cells that have a channelrhodopsin, or opsin, protein. In sonogenetics, we wanted a protein that would let us have that same level of cellular control. But finding that protein has been difficult. Lots of groups have been looking for these proteins, and we were fortunate to find one. © 2022 Simons Foundation

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28227 - Posted: 03.02.2022

Natalia Mesa More than a decade ago, scientists developed optogenetics, a method to turn cells on and off with light. The technique allows scientists to spur or suppress cells' electrical activity with just the flip of a switch to tease apart the roles of specific cell types. But because light doesn’t penetrate deep into tissues, scientists need to surgically implant light sources to illuminate cells below the surface of the skin or skull. In a new study published today (February 9) in Nature Communications, researchers report they’ve found a way to use ultrasound to noninvasively activate mouse neurons, both in culture and in the brains of living animals. The technique, which the authors call sonogenetics, elicits electrical activity in a subset of brain cells that have been genetically engineered to respond to sound waves. “We know that ultrasound is safe,” study coauthor Sreekanth Chalasani, a neuroscientist in Salk’s Molecular Neurobiology Laboratory, tells The Scientist. “The potential for neuronal control is huge. It has applications for pacemakers, insulin pumps, and other therapies that we’re not even thinking about. Jamie Tyler, a biomedical engineer at the University of Alabama at Birmingham who was not involved in the study but has previously collaborated with some of its authors, tells The Scientist that the work represents “more than just a step forward” in being able to use ultrasound to control neural activity: “It shows that sonogenetics is a viable technique in mammalian cells.” © 1986–2022 The Scientist.

Related chapters from BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28199 - Posted: 02.12.2022

In 2016, Science magazine ranked Randy L. Buckner among the top 10 most influential brain scientists of the modern era. He explains the road to discovering the default network, the pattern of brain activity triggered as we think about the past and the future. Q: Why don’t we begin with a brief description of what the default network is, how and when it was discovered, and why it’s important. Randy L. Buckner: In the 1990s, neuroscientists were just starting to do functional imaging studies. For the first time, we had brain scanners that could see the mind at work. We were like kids in a candy store in the sense that we no longer needed a scalpel to see the brain; the new technology allowed us to safely discern information out about what parts of the brain people used when given different tasks and different kinds of visual or auditory stimuli. I was a graduate student at the time at Washington University and one of my mentors, Marcus Raichle, was at the forefront of positron emission tomography (PET), an imaging technique that measures physiological changes in the brain and shows where blood flow is increasing due to brain activity. This is when many of us first became aware of the Dana Foundation, which was helping fund our work. I was a Dana fellow in those early days, and this was an exciting time in neuroscience. In early studies, we often asked participants to perform very simple tasks: read and say words, detect colors in pictures, or try to recognize whether a viewed word was on an earlier studied list. The imaging revealed the parts of the brain involved in their responses. But what jumped out at us was something unexpected: When people weren’t asked for a response or given a specific task, much of their brain still remained active. © 2022 The Dana Foundation.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28171 - Posted: 01.26.2022

Rupert Neate The billionaire entrepreneur Elon Musk’s brain chip startup is preparing to launch clinical trials in humans. Musk, who co-founded Neuralink in 2016, has promised that the technology “will enable someone with paralysis to use a smartphone with their mind faster than someone using thumbs”. The Silicon Valley company, which has already successfully implanted artificial intelligence microchips in the brains of a macaque monkey named Pager and a pig named Gertrude, is now recruiting for a “clinical trial director” to run tests of the technology in humans. “As the clinical trial director, you’ll work closely with some of the most innovative doctors and top engineers, as well as working with Neuralink’s first clinical trial participants,” the advert for the role in Fremont, California, says. “You will lead and help build the team responsible for enabling Neuralink’s clinical research activities and developing the regulatory interactions that come with a fast-paced and ever-evolving environment.” Musk, the world’s richest person with an estimated $256bn fortune, said last month he was cautiously optimistic that the implants could allow tetraplegic people to walk. “We hope to have this in our first humans, which will be people that have severe spinal cord injuries like tetraplegics, quadriplegics, next year, pending FDA [Food and Drug Administration] approval,” he told the Wall Street Journal’s CEO Council summit. “I think we have a chance with Neuralink to restore full-body functionality to someone who has a spinal cord injury. Neuralink’s working well in monkeys, and we’re actually doing just a lot of testing and just confirming that it’s very safe and reliable and the Neuralink device can be removed safely.” © 2022 Guardian News & Media Limited

Related chapters from BN: Chapter 11: Motor Control and Plasticity; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28164 - Posted: 01.22.2022

Monique Brouillette Last summer a group of Harvard University neuroscientists and Google engineers released the first wiring diagram of a piece of the human brain. The tissue, about the size of a pinhead, had been preserved, stained with heavy metals, cut into 5,000 slices and imaged under an electron microscope. This cubic millimeter of tissue accounts for only one-millionth of the entire human brain. Yet the vast trove of data depicting it comprises 1.4 petabytes’ worth of brightly colored microscopy images of nerve cells, blood vessels and more. “It is like discovering a new continent,” said Jeff Lichtman of Harvard, the senior author of the paper that presented these results. He described a menagerie of puzzling features that his team had already spotted in the human tissue, including new types of cells never seen in other animals, such as neurons with axons that curl up and spiral atop each other and neurons with two axons instead of one. These findings just scratched the surface: To search the sample completely, he said, would be a task akin to driving every road in North America. Lichtman has spent his career creating and contemplating these kinds of neural wiring diagrams, or connectomes — comprehensive maps of all the neural connections within a part or the entirety of a living brain. Because a connectome underpins all the neural activity associated with a volume of brain matter, it is a key to understanding how its host thinks, feels, moves, remembers, perceives, and much more. Don’t expect a complete wiring diagram for a human brain anytime soon, however, because it’s technically infeasible: Lichtman points out that the zettabyte of data involved would be equivalent to a significant chunk of the entire world’s stored content today. In fact, the only species for which there is yet a comprehensive connectome is Caenorhabditis elegans, the humble roundworm. Nevertheless, the masses of connectome data that scientists have amassed from worms, flies, mice and humans are already having a potent effect on neuroscience. And because techniques for mapping brains are getting faster, Lichtman and other researchers are excited that large-scale connectomics — mapping and comparing the brains of many individuals of a species — is finally becoming a reality. Share this article Simons Foundation All Rights Reserved © 2021

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 28104 - Posted: 12.08.2021

Yongsoo Kim The brain plays an essential role in how people navigate the world by generating both thought and behavior. Despite being one of the most vital organs of life, it takes up only 2% of human body volume. How can something so small perform such complex tasks? Luckily, modern tools like brain mapping have allowed neuroscientists like me to answer this exact question. By mapping out how all the cell types in the brain are organized and examining how they communicate with one another, neuroscientists can better understand how brains normally work, and what happens when certain cell parts go missing or malfunction. The task of understanding the inner workings of the brain has fascinated both philosophers and scientists for centuries. Aristotle proposed that the brain is where spirit resides. Leonardo da Vinci drew anatomical depictions of the brain with wax embedding. And Santiago Ramón y Cajal, with his 1906 Nobel Prize-winning work on the cellular structure of the nervous system, made one of the first breakthroughs that led to modern neuroscience as we know it. Using a new way to visualize individual cells called Golgi staining, a method pioneered by Nobel co-winner Camillo Golgi, and microscopic examination of brain tissue, Cajal established the seminal neuron doctrine. This principle states that neurons, among the main types of brain cells, communicate with one another via the gaps between them called synapses. These findings launched a race to understand the cellular composition of the brain and how brain cells are connected to one another. Conversation US, Inc.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28085 - Posted: 11.20.2021

Kate Wild “The skull acts as a bastion of privacy; the brain is the last private part of ourselves,” Australian neurosurgeon Tom Oxley says from New York. Oxley is the CEO of Synchron, a neurotechnology company born in Melbourne that has successfully trialled hi-tech brain implants that allow people to send emails and texts purely by thought. In July this year, it became the first company in the world, ahead of competitors like Elon Musk’s Neuralink, to gain approval from the US Food and Drug Administration (FDA) to conduct clinical trials of brain computer interfaces (BCIs) in humans in the US. Synchron has already successfully fed electrodes into paralysed patients’ brains via their blood vessels. The electrodes record brain activity and feed the data wirelessly to a computer, where it is interpreted and used as a set of commands, allowing the patients to send emails and texts. BCIs, which allow a person to control a device via a connection between their brain and a computer, are seen as a gamechanger for people with certain disabilities. “No one can see inside your brain,” Oxley says. “It’s only our mouths and bodies moving that tells people what’s inside our brain … For people who can’t do that, it’s a horrific situation. What we’re doing is trying to help them get what’s inside their skull out. We are totally focused on solving medical problems.” BCIs are one of a range of developing technologies centred on the brain. Brain stimulation is another, which delivers targeted electrical pulses to the brain and is used to treat cognitive disorders. Others, like imaging techniques fMRI and EEG, can monitor the brain in real time. “The potential of neuroscience to improve our lives is almost unlimited,” says David Grant, a senior research fellow at the University of Melbourne. “However, the level of intrusion that would be needed to realise those benefits … is profound”. © 2021 Guardian News & Media Limited

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 15: Language and Lateralization
Link ID: 28070 - Posted: 11.09.2021